Devices and methods of preventing plasma charging damage in semiconductor devices

ABSTRACT

Methods for protecting semiconductor devices from plasma charging damage are disclosed. An example disclosed method includes depositing an etching stop layer on a substrate with at least one predetermined structure; depositing a premetallic dielectric layer and a charge preservation layer on the entire surface of the etching stop layer; depositing an insulating layer on the surface of the resulting structure; and forming an metallic interconnect on the insulating layer.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor fabricationand, more particularly, to devices and methods of preventing plasmacharging damage in semiconductor devices.

BACKGROUND

The use of plasma in semiconductor device fabrication providesdirectionality, low temperature, and processing convenience.Accordingly, plasma is typically used in etch and deposition processesfor fabricating semiconductor devices. However, the plasma alsointroduces a potential for increased semiconductor damage due to surfacecharging of a semiconductor device. This surface charging during theplasma processing is often referred to as plasma charging damage. As thethickness of a gate oxide layer continue to decrease to improve deviceperformance, the plasma charging damage is becoming a large concernbecause it can severely and directly degrade the electrical propertiesof the gate oxide layer. Especially, after the formation of a firstmetallic interconnect having the highest antenna ratio among metallicinterconnects and in contact with a transistor, the probability of theoccurrence of the plasma charging damage is getting greater. However, aconventional Pre-Metallic Dielectric (PMD) layer does not contain anymaterial that can prevent the occurrence of the plasma charging damage.

Referring to FIG. 1, a conventional PMD layer including a nitride layer11 as an etching stop layer, a BPSG layer 12, and an oxide layer 13 as acapping layer are placed on a substrate with at least one structure. Ametallic interconnect 14 is placed on the PMD layer. A first Inter-LayerDielectric (ILD) 15, a second insulating layer 16, a second metallicinterconnect 17, and a second ILD 18 are sequentially and repeatedlyplaced on the device.

However, the nitride layer 11, the BPSG 12, and the oxide layer 13 haveshortcomings such as poor charge preservation and are, therefore, unableto protect the semiconductor device from the plasma charging damage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a known structure affectedby the plasma charging damages.

FIGS. 2 a and 2 b are cross-sectional views illustrating devicesconstructed in accordance with disclosed methods for preventing plasmacharging damages.

DETAILED DESCRIPTION

Referring to FIG. 2 a, a gate oxide layer 22 is grown on a substrate 21.Next, a gate electrode 23 is formed on the gate oxide layer 22.Subsequently, a Lightly Doped Drain (LDD) structure 25 is formed aroundthe gate electrode 23 by an ion implantation process by using the gateelectrode 23 and the gate oxide layer 22 as a mask. Spacers 26 areformed on the lateral faces of the gate electrodes. Source and drainregions 24 having the LDD structure 25 are then formed around the gateelectrode 23. A nitride layer 27 is then formed on the resultingstructure.

Subsequently, a charge preservation layer 28 is formed on the nitridelayer 27 to prevent the deterioration of the gate oxide layer by chargesinduced from a first metallic interconnect or a second metallicinterconnect. The charge preservation layer 28 may be polysilicon andmay be formed by a plasma treatment or a thermal treatment. The chargepreservation layer 28 may have a thickness between 150 Å and 1000 Å, tosuppress the increase in delay time generated by a capacitance.

Next, a BPSG layer 29 is deposited on entire surface of the chargepreservation layer 28. A first oxide layer 30 and the first metallicinterconnect 31, a first ILD 32, a second oxide layer 33, the secondmetallic interconnect 34, and a second ILD 35 are sequentially formed.If more layers are required, the identical process as described abovewill be performed sequentially and repeatedly.

Referring to FIG. 2 b, a charge preservation layer is deposited afterthe depostion of a BPSG layer. In detail, a gate oxide layer 22 is grownon a substrate 21. Next, a gate electrode is formed on the surface ofthe gate oxide layer 22. Subsequently, an LDD structure 25 is formedaround the gate electrode 23 by an ion implantation process by using thegate electrode 23 and the gate oxide layer 22 as mask. Spacers 26 areformed on the lateral faces of the gate electrodes 23. Source and drainregions 24 having the LDD structure 25 are then formed around the gateelectrode 22. A nitride layer 27 is then formed on the resultingstructure.

Next, a BPSG layer 29 is formed on entire surface of the resultingstructure. The charge preservation layer 28 made of polysilicon with thesame objective as described is then deposited on the BPSG layer 29.Thus, the device for preventing plasma charging damages, as disclosedherein is constructed as follows.

Accordingly, by means of forming a BPSG layer before or after thedeposition of the charge preservation layer, the disclosed methods andapparatus provide the methods for preventing plasma charging damagessuch as the deterioration of the gate oxide layer due to theplasma-induced charge through metallic interconnects on the gateelectrode. In addition, the methods disclosed herein can improve theTime Dependent Dielectric Breakdown (TDDB) of the semiconductor deviceand suppress leakage current, thereby increasing the reliability of thesemiconductor device. An etching stop layer is placed on a substratewith at least one predetermined structure. A premetallic dielectriclayer and a charge preservation layer are placed on the entire surfaceof the etching stop layer. An insulating layer is positioned on thesurface of the resulting structure. A metallic interconnect is placed onthe insulating layer.

It is noted that this patent claims priority from Korean PatentApplication Serial Number 10-2003-01012998, which was filed on Dec. 31,2003, and is hereby incorporated by reference in its entirety.

Although certain example methods, apparatus, and articles of manufacturehave been described herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus, and articles of manufacture fairly falling within the scopeof the appended claims either literally or under the doctrine ofequivalents.

1. A method for preventing plasma charging damages comprising:depositing an etching stop layer on a substrate with at least onepredetermined structure; depositing a premetallic dielectric layer and acharge preservation layer on the entire surface of the etching stoplayer; depositing an insulating layer on the surface of the resultingstructure; and forming an metallic interconnect on the insulating layer.2. A method as defined by claim 1, wherein the etching stop layercomprises a silicon nitride layer.
 3. A method as defined by claim 1,wherein the premetallic dielectric layer comprises BPSG.
 4. A method asdefined by claim 1, wherein the charge preservation layer comprisespolysilicon.
 5. A method as defined by claim 1, wherein the premetallicdielectric layer is deposited after the deposition of the chargepreservation layer.
 6. A method as defined by claim 1, wherein thepremetallic dielectric layer is deposited before the deposition of thecharge preservation layer.
 7. A method as defined by claim 1, whereinthe charge preservation layer is deposited with a thickness betweenabout 150 Å and about 1000 Å.
 8. A device for preventing plasma chargingdamages comprising: an etching stop layer on a substrate with at leastone predetermined structure; a premetallic dielectric layer and a chargepreservation layer on the entire surface of the etching stop layer; aninsulating layer on the surface of the resulting structure; and ametallic interconnect on the insulating layer.
 9. A device as defined byclaim 8, wherein the premetallic dielectric layer is placed on thecharge preservation layer.
 10. A method as defined by claim 8, whereinthe premetallic dielectric layer is placed under the charge preservationlayer.
 11. A method as defined by claim 8, wherein the chargepreservation layer has a thickness between about 150 Å and about 1000 Å.